A tale of many neighborhoods: Latent profile analysis to derive a national neighborhood typology for the US

INTRODUCTION

Neighborhoods are complex and multi-faceted. Analytic strategies used to model neighborhoods should reflect this complexity, with the potential to better understand how neighborhood characteristics together impact health. We used latent profile analysis (LPA) to derive a residential neighborhood typology applicable for census tracts across the US.

METHODS

From tract-level 2015-2019 American Community Survey (ACS) five-year estimates, we selected five indicators that represent four neighborhood domains: demographic composition, commuting, socioeconomic composition, and built environment. We compared model fit statistics for up to eight profiles to identify the optimal number of latent profiles of the selected neighborhood indicators for the entire US. We then examined differences in national tract-level 2019 prevalence estimates of physical and mental health derived from CDC's PLACES dataset between derived profiles using one-way analysis of variance (ANOVA).

RESULTS

The 6-profile LPA model was the optimal categorization of neighborhood profiles based on model fit statistics and interpretability. Neighborhood types were distinguished most by demographic composition, followed by commuting and built environment domains. Neighborhood profiles were associated with meaningful differences in the prevalence of health outcomes. Specifically, tracts characterized as "Less educated non-immigrant racial and ethnic minority active transiters" (n = 3,132, 4%) had the highest poor health prevalence (Mean poor physical health: 18.6 %, SD: 4.30; Mean poor mental health: 19.6 %, SD: 3.85), whereas tracts characterized as "More educated metro/micropolitans" (n = 15, 250, 21%) had the lowest prevalence of poor mental and physical health (Mean poor physical health: 10.6 %, SD: 2.41; Mean poor mental health: 12.4 %, SD: 2.67; p < 0.001).

CONCLUSION

LPA can be used to derive meaningful and standardized profiles of tracts sensitive to the spatial patterning of social and built conditions, with observed differences in mental and physical health by neighborhood type in the US.

Test-retest reliability of the two-point discrimination test on the sole of the foot in people with multiple sclerosis

BACKGROUND

Two-point discrimination (TPD) is an assessment of tactile acuity. People with multiple sclerosis (MS) can have reduced foot sole tactile acuity, which has been linked to impaired balance.

OBJECTIVE

To quantify the test-retest reliability of TPD on the sole of the foot in people with MS.

APPROACH

41 participants (32 females), with mean (SD) age of 60 (9) years, and Expanded Disability Status Scale of <7.5, had their TPD measured at the head of the first metatarsal and the heel on two occasions, 2-14 d apart. Mean systematic change, within-subjects SD, limits of agreement (LOA), coefficient of variation and the intraclass correlation coefficient (ICC) were quantified as point estimates (95% CI).

MAIN RESULTS

Systematic learning effects were evident. The within-subjects SD at the metatarsal and the heel was 6.7 mm (5.5-8.6) and 8.3 mm (6.7-10.8), and the LOAs were 18.6 mm (15.2-24.) and 23.7 mm (18.7-30.1), respectively. ICCs for metatarsal and heel was 0.87 (0.76-0.93) and 0.90 (0.80-0.95), respectively, but these were likely inflated by sample heterogeneity.

SIGNIFICANCE

In people with MS, TPD on the sole of the foot has an adequate test-retest reliability for research purposes, but there is substantial measurement variability for individual patients.

Abstract C068: Census tract-level income inequality and colorectal cancer survival

Background: Income inequality has been associated with greater mortality and lower life expectancy in many ecologic studies, particularly at the national level. At the neighborhood level, the influence of income inequality on individual health is less clear. Colorectal cancer (CRC) is the second leading cause of cancer death in the United States. Recent studies suggest that neighborhood social and built environments are associated with outcomes across the CRC continuum, including screening, risk, and survival. Few studies of neighborhood factors have examined income inequality in relation to CRC survival.

Methods: We examined the association of census tract-level income inequality with survival among women who participated in the Women's Health Initiative (WHI) and were diagnosed with incident invasive CRC between 1994-2014 (N=2,595). Based on geocoded residence at diagnosis and year of diagnosis, we linked each participant to census tract-level data from the US Census and American Community Survey (ACS). Within each tract, income inequality was assessed using the ratio of the 95th and 20th percentiles for household income. Quartiles for 95/20 ratio were constructed from the distribution of 95/20 ratios across all U.S. census tracts with more than 50 households. We used Cox proportional hazards regression models to estimate hazard ratios (HR) and 95% confidence intervals (CI) for overall and disease-specific survival. Models were adjusted for age at diagnosis, year of diagnosis, individual household income, and tract-level percent of households in poverty; subsequent models also adjusted for tumor stage at diagnosis. To explore whether the relationship between income inequality and survival differed by individual or tract-level sociodemographic characteristics, we conducted analyses stratified by race/ethnicity, individual household income, and tract-level poverty.

Results: Compared to women residing in low-income-inequality census tracts, women living in tracts with the highest income inequality had modestly poorer overall survival (HR=1.24, 95% CI: 1.01-1.51, comparing highest and lowest quartiles). However, this association was not significant after adjustment for stage at diagnosis. No associations were detected for disease-specific survival. The associations between income inequality and overall or disease-specific survival were not modified by tract-level poverty, individual household income, or race/ethnicity.

Conclusion: There was no association between census tract-level income inequality and CRC survival in our study. Our results suggest that the association may be confounded or even mediated by disparities in stage at diagnosis.

Citation Format: Kelsey A. Chun, Jamaica R. Robinson, Candace H. Kroenke, Dorothy S. Lane, Giselle Corbie-Smith, Theresa Hastert, Shawnita Sealy-Jefferson, Manali I. Patel, Kathy Pan, Shirley A.A. Beresford, Polly A. Newcomb. Census tract-level income inequality and colorectal cancer survival [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C068.

Leptin gene variants and colorectal cancer risk: Sex-specific associations

BACKGROUND

High levels of serum leptin and low levels of serum adiponectin are strongly correlated with obesity, a well-established risk factor for colorectal cancer (CRC). Growing evidence suggests that dysregulation of leptin and adiponectin levels may play an etiological role in colorectal carcinogenesis. We evaluated 20 candidate variants in 4 genes previously shown to alter serum leptin and adiponectin levels for associations with obesity (BMI>30 kg/m2) and CRC risk.

METHODS

We analyzed 6,246 CRC cases and 7,714 population-based controls from 11 studies within the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO). Associations of each variant with obesity or CRC were evaluated using multivariate logistic regression models stratified by sex and adjusted for age, a study variable, and the first three principal components of genetic ancestry. Gene-specific False Discovery Rate (FDR)-adjusted p-values <0.05 denoted statistical significance.

RESULTS

Two variants in the leptin gene showed statistically significant associations with CRC among women: LEP rs2167270 (OR = 1.13, 95% CI: 1.06-1.21) and LEP rs4731426 (OR = 1.09, 95% CI: 1.02-1.17). These associations remained significant after adjustment for obesity, suggesting that leptin SNPs may influence CRC risk independent of obesity. We observed statistically significant interactions of the leptin variants with hormone replacement therapy (HRT) for CRC risk; these variant associations were strengthened when analyses were restricted to post-menopausal women with low estrogen exposure, as estimated by 'never use' of HRT and/or non-obese BMI. No variants were associated with CRC among men.

CONCLUSIONS

Leptin gene variants may exhibit sex-specific associations with CRC risk. Endogenous and exogenous estrogen exposure may modify the association between these variants, leptin levels, and CRC risk.

The Avon patellofemoral joint arthroplasty: two- to 18-year results of a large single-centre cohort

Aims

This study reports on the medium- to long-term implant survivorship and patient-reported outcomes for the Avon patellofemoral joint (PFJ) arthroplasty.

Patients and Methods

A total of 558 Avon PFJ arthroplasties in 431 patients, with minimum two-year follow-up, were identified from a prospective database. Patient-reported outcomes and implant survivorship were analyzed, with follow-up of up to 18 years.

Results

Outcomes were recorded for 483 implants (368 patients), representing an 86% follow-up rate. The median postoperative Oxford Knee Score (0 to 48 scale) was 35 (interquartile range (IQR) 25.5 to 43) and the median Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC, 0 to 100 scale) was 35 (IQR 25 to 53) at two years. There were 105 revisions, 61 (58%) for progression of osteoarthritis. All documented revisions were to primary knee systems without augmentation. The implant survival rate was 77.3% (95% confidence interval (CI) 72.4 to 81.7, number at risk 204) at ten years and 67.4% (95% CI 72.4 to 81.7 number at risk 45) at 15 years. Regression analysis of explanatory data variable showed that cases performed in the last nine years had improved survival compared with the first nine years of the cohort, but the individual operating surgeon had the strongest effect on survivorship.

Conclusion

Satisfactory long-term results can be obtained with the Avon PFJ arthroplasty, with maintenance of patient-reported outcome measures (PROMs), satisfactory survival, and low rates of loosening and wear. Cite this article: Bone Joint J 2018;100-B:1162-7.

Stage IV colorectal cancer primary site and patterns of distant metastasis

BACKGROUND

Although colorectal cancer (CRC) usually metastasizes to the liver and/or lungs, factors influencing the anatomic pattern of metastases remain poorly understood.

METHODS

We assessed the relationship between primary CRC site and pattern of synchronous metastasis among 1202 individuals diagnosed with incident metastatic CRC between 2010 and 2014 and identified through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results (SEER) registry. Polytomous logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association between primary tumor site and synchronous metastatic pattern.

RESULTS

Compared to patients with proximal colon primaries, patients with rectal primaries were more likely to present with lungs-only or liver and lungs metastases versus liver-only metastases (OR_{lungs-onlyvs.liver-only}: 2.39, 95% CI: 1.35-4.24, OR_{liver+lungsvs.liver-only}: 2.20, 95% CI: 1.46-3.32).

CONCLUSION

These findings suggest that patients with rectal primaries are more likely than patients with colon primaries to present with synchronous lung metastases.

Survivorship and clinical outcome of the minimally invasive Uniglide medial fixed bearing, all-polyethylene tibia, unicompartmental knee arthroplasty at a mean follow-up of 7.3years

BACKGROUND

Medial UKA performed in England and Wales represents seven to 11% of all knee arthroplasty procedures, and is most commonly performed using mobile-bearing designs. Fixed bearing eliminates the risk of bearing dislocation, however some studies have shown higher revision rates for all-polyethylene tibial components compared to those that utilize metal-backed implants. The aim of the study is to analyse survivorship and maximum eight-year clinical outcome of medial fixed bearing, Uniglide unicompartmental knee arthroplasty performed using an all-polyethylene tibial component with a minimal invasive approach.

METHODS

Between 2002 and 2009, 270 medial fixed UKAs were performed in our unit. Patients were reviewed pre-operatively, five and eight years post-operatively. Clinical and radiographic reviews were carried out. Patients' outcome scores (Oxford, WOMAC and American Knee Score) were documented in our database and analysed.

RESULTS

Survival and clinical outcome data of 236 knees with a mean of 7.3years follow-up are reported. Every patient with less than 4.93years of follow-up underwent a revision. The patients' average age at the time of surgery was 69.5years. The American Knee Society Pain and Function scores, the Oxford Knee Score and the WOMAC score all improved significantly. The five-year survival rate was 94.1% with implant revision surgery as an end point. The estimated 10years of survival rate is 91.3%. Fourteen patients were revised before the five-year follow-up.

CONCLUSION

Fixed bearing Uniglide UKA with an all-polyethylene tibial component is a valuable tool in the management of a medial compartment osteoarthritis, affording good short-term survivorship. Level of evidence IV.

Prediagnostic alcohol consumption and colorectal cancer survival: The Colon Cancer Family Registry

BACKGROUND

Although previous studies have noted an increased risk of colorectal cancer (CRC) among moderate to heavy alcohol consumers in comparison with nondrinkers, the relation between alcohol consumption and CRC survival remains unclear.

METHODS

Cases of incident invasive CRC diagnosed between 1997 and 2007 were identified via population-based cancer registries at 4 study sites in the Colon Cancer Family Registry. Study participants completed a risk-factor questionnaire on prediagnostic behaviors, including wine, beer, and liquor consumption, at the baseline. Prospective follow-up for survival was conducted for 4966 CRC cases. Cox regression was used to compare nondrinkers with individuals who consumed, on average, 1 or more servings of alcohol per day in the years preceding their CRC diagnosis with respect to overall and disease-specific survival. Separate analyses by beverage type, stratified by patient and tumor attributes, were also performed. All models were adjusted for the age at diagnosis, sex, study site, year of diagnosis, smoking history, body mass index, and education.

RESULTS

Prediagnostic beer and liquor consumption was not associated with CRC survival; however, higher levels of wine consumption were modestly associated with a better prognosis overall (CRC-specific hazard ratio [HR], 0.70, 95% confidence interval [CI], 0.48-1.03; overall HR, 0.70; 95% CI, 0.53-0.94). Similar patterns were noted in stratified analyses.

CONCLUSIONS

These findings suggest that prediagnostic wine consumption is modestly associated with more favorable survival after CRC. Cancer 2017;123:1035-43. © 2016 American Cancer Society.

Abstract 5214: Stage IV colorectal cancer sub-site and patterns of distant metastases

Approximately 20% of individuals diagnosed with colorectal cancer (CRC) in the United States are found to have distant metastases at the time of their diagnosis, indicating an extremely poor prognosis. Although it is well known that primary CRC typically metastasizes to the liver and/or lungs, little is known regarding which factors might explain the anatomic pattern of CRC metastatic spread. Using population-based registry data from the Surveillance, Epidemiology and End Results (SEER) cancer registry of the Seattle-Puget Sound region, we assessed the relationship between primary CRC sub-site and the presence of synchronous metastases in the liver, lungs, and both the liver and lungs. All individuals with stage IV CRC who were diagnosed between 2010-2014 in the 13-county catchment area and who also had complete data on site of metastasis at diagnosis were included in analyses (N = 1287). In total, 703 (55%) patients had distant metastases confined to the liver at the time of diagnosis, 78 (6%) had lung-only metastases, 190 (15%) had metastases in both the liver and lungs but not at other sites, and 316 (25%) exhibited different patterns of metastatic spread, including to the bone, brain, and other anatomic sites. Using multiple logistic regression models, we compared individuals with different patterns of metastatic spread at diagnosis with respect to primary CRC site and with separate models comparing cases with liver-only metastases to all other metastatic cases, comparing cases with lung-only metastases to all other metastatic cases, and comparing cases with metastases to both the liver and lungs to all other metastatic CRC cases. All models were adjusted for age at diagnosis and sex, as well as for depth of primary tumor growth within the colorectum (T-stage) and extent of cancer spread to lymph nodes (N-stage). The odds of having a primary CRC tumor in the rectum, versus proximal colon, were significantly lower among patients with liver-only synchronous metastases relative to those with other patterns of metastatic spread at diagnosis [odds ratio (OR): 0.62, 95% confidence interval (CI): 0.46 - 0.82]. Conversely, the odds of having a primary CRC located in the rectum were significantly higher among those with metastatic disease confined to the lungs (OR: 2.48, 95% CI: 1.38 - 4.47) and those with metastases to the liver and lungs (OR: 1.97, 95% CI: 1.29 - 3.01). Our findings suggest that a patient's site of primary CRC may be informative with respect to possible pattern of metastatic spread.

Citation Format: Jamaica R. Robinson, Polly A. Newcomb, Sheetal Hardikar, Stacey A. Cohen, Amanda I. Phipps. Stage IV colorectal cancer sub-site and patterns of distant metastases. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5214.

Bristol index of patellar width to thickness (BIPWiT): a reproducible measure of patellar thickness from adult MRI

BACKGROUND

The restoration of an adequate patellar thickness is a key to the successful outcome of knee arthroplasty. This study investigated the relationship between the thickness of the native patellar and medial-lateral patellar width using magnetic resonance imaging (MRI).

METHODS

75 MRI scans of young adults, with an average age of 27 (range 16-40) were studied. Exclusion criteria included a diagnosis of degenerative joint disease, patello-femoral pathology or age under 16/over 40 (170 patients). The bony thickness of the patellar, the chondral thickness and patellar width were measured, as was the location of maximal patellar thickness. Inter/intraobserver variability was calculated and correlation analysis was performed.

RESULTS

We found a strong correlation between patellar width and thickness (bone plus cartilage) (Pearson 0.75, P<0.001). The mean width to thickness ratio was 1.8:1 (standard deviation 0.1, 95% confidence interval 1.78-1.83). Without cartilage the ratio was 2.16:1 (SD 0.15, 95% CI 2.11-2.21), correlation was moderate (Pearson 0.59, P<0.001). The average maximal patellar cartilage thickness was 4.1mm (SD 1.3).

CONCLUSION

The strong correlation and narrow confidence intervals for the ratio of patellar width to thickness, suggest that patellar width might be used as a guide for accurate restoration of patellar thickness during total knee or patello-femoral replacement. After removing osteophytes we would recommend a ratio of 1.8:1. Further work is required to establish whether there is a relationship between anterior knee pain post total knee arthroplasty and an abnormal patellar width:thickness ratio.

LEVEL OF EVIDENCE

Level III.

Do long leg supine CT scanograms correlate with weight-bearing full-length radiographs to measure lower limb coronal alignment?

INTRODUCTION

The gold standard for measuring knee alignment is the lower limb mechanical axis (MA) using weight-bearing lower limb full-length x-ray (FLX). However, CT scanograms (CTS) are becoming increasingly popular in view of lower radiation exposure, speed of data acquisition and supine positioning. We compared the correlation and degree of agreement of knee joint coronal alignment using these two imaging modalities.

METHOD

From our series of complex primary and revision knee arthroplasty patients, we selected those with both FLX and CTS recorded onto digital PACS. The coronal alignments were assessed in 24 knees and the valgus/varus angles relative to the MA were measured. Results were analysed statistically using the paired samples t-test, Pearson's correlation coefficient, intra-class correlation coefficient, Cohen's kappa and Passing and Bablok regression to assess potential equality of methods.

RESULTS

The mean MA was 180.5° (165°-200°) for the CTS and 181° (164°-202°) for the FLX. The CTS MA angle data between the assessors were highly correlated (r=0.971, p <0.001) as were FLX MA angle measurements (r=0.988, p <0.001). 41.7% of the CTS and 37.5% of the FLX were in varus alignment, while 50% of the CTS and 43.8% of the FLX were in valgus alignment. Malalignment >5° was revealed by 18.8% of the CTS and 35.4% of the FLX.

CONCLUSION

Overall, good agreement was observed in MA angle data between the two imaging modalities, but reproducibility may be problematic. In the malaligned limb, weight-bearing FLX still remains a vital imaging modality. CTS should be used with caution in view of the under-detection of malalignment.

Early failure of a mobile-bearing unicompartmental knee replacement

Concerned by a perceived high revision rate, we retrospectively reviewed the survivorship of a series of 43 cemented, medial, mobile-bearing Preservation unicompartmental knee replacements implanted during a 2-year period at a single institution. The initial post-operative AP and lateral radiographs were independently assessed to test the hypothesis that suboptimal implantation of the prosthesis was responsible for early failure. An X-ray scoring system based on the criteria for assessing the Oxford mobile-bearing unicompartmental knee replacement was devised. The components of this score included assessment of prosthesis alignment, sizing and cementation. Nine (21%) LCS Preservation mobile-bearings prostheses had required revision at a mean of 22 months post-implantation. The commonest causes for failure were pain (44%) and tibial component loosening (33%). Analysis of post-operative radiographs showed no difference (n.s.) between the compound error scores for the revised and the surviving prostheses. No particular surgical error was identifiable leading to subsequent need for revision. The high failure rates shown in this study have led us to cease using this implant. The clinical relevance of this study is that the captive running track of the LCS mobile-bearing prosthesis may over constrain the meniscal component leading to early failure.

Rheological, mucoadhesive and release properties of pluronic F-127 gel and pluronic F-127/polycarbophil mixed gel systems

This study was designed to combine the mucoadhesive property of Noveon and the thermosensitive property of Pluronic F-127 into one gel system. A rheological study of Pluronic aqueous sols (10-35%), Noveon gels (0.5-2%) and of mixed gels containing Pluronic (10-17.5%) and polycarbophil (0.5-2.5%) was conducted at different temperatures (15-35 degrees C). The viscosity of Pluronic sols increased with an increase in temperature and the mixed gels had thermoreversible property. The viscosity of mixed gels was higher than that of the Pluronic sols containing only Pluronic because of the increase in total polymer concentration. No interaction was found between -COOH groups of Noveon and Pluronic molecules at the studied concentrations of polymers; the viscosity of mixed gels containing un-neutralized Noveon was lower than that of the neutralized mixed gels. The effect of Pluronic F-127 on the mucoadhesive property of Noveon was investigated. The mucoadhesive properties of Pluronic and Noveon gels were compared by a force of detachment test. It was found that Pluronic and Noveon gels showed approximately the same mucoadhesive strength. However, there were significant differences in the viscosity of Noveon and Pluronic gels. The adhesive force of the mixed gel was almost same as that of the Noveon gel. The Pluronic did not affect the adhesive power of Noveon and the increased viscosity did not affect the bioadhesive force of the mixed gels. In spite of increasing viscosity of the gel, the percentage of released model material (mannitol) increased with increasing temperature. This is based on the previously reported observation that the interaction between the Pluronic molecules squeezed mannitol molecules out of the polymer chains. The mannitol release obeyed zero-order kinetics and the flux values of mixed gels at 15 and 35 degrees C were very similar. The Noveon chains among Pluronic chains probably hindered the diffusion of mannitol molecules and the release was thus controlled by Noveon. The combination of a thermosensitive polymer like Pluronic and a bioadhesive polymer like Noveon appears promising from a pharmaceutical viewpoint. These gel systems may find use in the development of bioadhesive, thermosensitive and controlled release formulations.

The posteromedial corner revisited

We have reviewed the literature on the anatomy of the posteromedial peripheral ligamentous structures of the knee and found differing descriptions. Our aim was to clarify the differing descriptions with a simplified interpretation of the anatomy and its contribution to the stability of the knee.

We dissected 20 fresh-frozen cadaver knees and the anatomy was recorded using video and still digital photography. The anatomy was described by dividing the medial collateral ligament (MCL) complex into thirds, from anterior to posterior and into superficial and deep layers. The main passive restraining structures of the posteromedial aspect of the knee were found to be superficial MCL (parallel, longitudinal fibres), the deep MCL and the posteromedial capsule (PMC). In the posterior third, the superficial and deep layers blend. Although there are oblique fibres (capsular condensations) running posterodistally from femur to tibia, no discrete ligament was seen. In extension, the PMC appears to be an important functional unit in restraining tibial internal rotation and valgus.

Our aim was to clarify and possibly simplify the anatomy of the posteromedial structures. The information would serve as the basis for future biomechanical studies to investigate the contribution of the posteromedial structures to joint stability.

Biomechanics of the PCL and related structures: posterolateral, posteromedial and meniscofemoral ligaments

This paper reviews and updates our knowledge of the anatomy and biomechanics of the posterior cruciate ligament, and of the posterolateral, posteromedial and meniscofemoral ligaments of the knee. The posterior cruciate ligament is shown to have two functional fibre bundles that are tight at different angles of knee flexion. It is the primary restraint to tibial posterior draw at all angles of knee flexion apart from near full extension. In contrast, the posterolateral and posteromedial structures are shown to tighten as the knee extends, and to be well-aligned to resist tibial posterior draw. These structures also act as primary restraints against other tibial displacements. Tibial internal rotation is restrained by the medial and posteromedial structures, while tibial external rotation is restrained by the lateral and posterolateral structures. They are also the primary restraints against tibial abduction-adduction rotations. The meniscofemoral ligaments are shown, for the first time, to contribute significantly to resisting tibial posterior draw, and to have a strength of approximately 300 N. Taken together, this evidence shows how the posterolateral and posteromedial structures are responsible for posterior knee stability near extension, and this, along with the action of the meniscofemoral ligaments, may explain why an isolated rupture of the posterior cruciate ligament does not often lead to knee instability

Drug delivery to the posterior segment of the eye: some insights on the penetration pathways after subconjunctival injection

The aim of this study is to gain an understanding of the penetration pathways for a drug to enter the posterior segment of the eye after subconjunctival injection. 14C-mannitol was injected subconjunctivally, and 14C-mannitol and 14C-inulin were injected intracamerally. The aqueous and vitreous levels were determined at selected time points. The results of subconjunctival injection and intracameral injection were compared. The vitreous level of the dosed eye is much higher than that of the corresponding contralateral eye after subconjunctival injection so that the recirculation pathway is not a dominant penetration pathway. In addition, the results also showed that it is unlikely for significant amounts of drug to move from the aqueous to the vitreous chamber after subconjunctival injection. Therefore, direct penetration is the dominant pathway for a subconjunctivally injected compound to enter the vitreous chamber.

Problem-solving abilities among mothers of infants with failure to thrive

OBJECTIVE

Maternal problem-solving abilities, as they related to specific child-rearing situations, were examined and compared among mothers of infants with failure to thrive (FTT) and a matched group of comparison mothers.

METHODS

Participants were 37 mothers of children diagnosed with FTT and 37 mothers with normally growing children matched on three child variables and five maternal variables. Participants were administered a means-ends problem-solving measure specific to parents of young children and measures of language ability, depression, negative affect, and stressful life events.

RESULTS

Multivariate analysis of covariance results supported our main study hypotheses that mothers of infants with FTT would generate fewer problem-solving strategies that would be judged of poorer quality (i.e., less likely to result in positive outcomes) than mothers of healthy, normally growing infants. There were no significant associations obtained among problem-solving variables and individual difference variables (e.g., depression, negative affect, and stressful life events).

CONCLUSIONS

Limited maternal problem-solving abilities may contribute to FTT by interfering directly with the quality of nurturance, feeling, and caloric intake the child receives. Recommendations are made for future research and interventions with mothers of children with FTT.

Feeding problems, sleep disturbances, and negative behaviors in a toddler

Tiffany, a 3-year-old girl, was referred to the developmental and behavioral pediatrics service for evaluation of significant and persistent negative behaviors associated with refusal to eat at meal time and constant snacking during the past 3 months. She lost 2 pounds, but her weight for her height was at the 50th percentile. Her mother indicated that Tiffany had frequent night awakenings (>10) and late sleep onset (between 12:00 and 1:00 a.m.). Her mother described her as being "easily frustrated," getting upset and angry very quickly. Tiffany was identified at an early intervention program as having mild to moderate developmental delays in pragmatic speech, gross and fine motor skills, and social interaction skills. Tiffany was born at 33 weeks gestation and was hospitalized for 10 days without significant perinatal problems. She was readmitted at 2 months of age when she was diagnosed with gastroesophageal reflux, lactose intolerance, sleep apnea, and bradycardia. She was discharged with an apnea monitor. A seizure disorder was diagnosed at 1 year of age and reactive airway disease at 2 years of age. At the time of the referral to the developmental and behavioral pediatrics service, Tiffany was followed by multiple services, including cardiology, neurology, gastroenterology, psychology, and pulmonary. Pharmacologic therapies included albuterol and cromalyn inhalers, phenobarbital, valproic acid, levocarnitine, ranitidine, and an inhaled steroid. She continued to use the apnea monitor each night, although three sleep studies demonstrated a normal sleep pattern with no evidence of apnea or bradycardia. A recent electroencephalogram was normal. Tiffany lives with her mother and maternal grandparents. Her mother is morbidly obese with a history of asthma and depression. She was infertile for a 10-year period, which she attributed to the stress associated with living with an abusive man. Tiffany was the result of a subsequent, brief relationship with another man; she has not had contact with her father. Her mother is a licensed practical nurse who has not worked as a nurse since Tiffany's birth. An interdisciplinary treatment approach to Tiffany's multiple biological and behavioral problems was implemented by admitting her to a collaborative care unit at a children's hospital.

Improvement in function after valgus bracing of the knee. An analysis of gait symmetry

The use of a valgus brace can effectively relieve the symptoms of unicompartmental osteoarthritis of the knee. This study provides an objective measurement of function by analysis of gait symmetry. This was measured in 30 patients on four separate occasions: immediately before and after initial fitting and then again at three months with the brace on and off. All patients reported immediate symptomatic improvement with less pain on walking. After fitting the brace, symmetry indices of stance and the swing phase of gait showed a consistent and immediate improvement at 0 and 3 months, respectively, of 3.92% (p = 0.030) and 3.40% (p = 0.025) in the stance phase and 11.78% (p = 0.020) and 9.58% (p = 0.005) in the swing phase. This was confirmed by a significant improvement at three months in the mean Hospital for Special Surgery (HSS) knee score from 69.9 to 82.0 (p < 0.001). Thus, wearing a valgus brace gives a significant and immediate improvement in the function of patients with unicompartmental osteoarthritis of the knee, as measured by analysis of gait symmetry.

Microbial populations, fermentation end-products, and aerobic stability of corn silage treated with ammonia or a propionic acid-based preservative

We studied the effects of ammonia treatment on microbial populations during the fermentation of corn silage. We also compared the effects of ammonia to a preservative containing buffered propionic acid and other antifungal compounds on the fermentation and aerobic stability of corn silage. In the first experiment, whole-plant corn was ensiled without treatment or treated with ammonia-N to supply an additional 0.3% N (fresh-forage basis). The addition of ammonia immediately increased silage pH and had no effect on numbers of lactic acid bacteria, but delayed their growth compared with untreated silage. Numbers of enterobacteria declined more slowly, but numbers of yeasts and molds declined more quickly in silage treated with ammonia. During the early stages of ensiling, lactic acid increased more rapidly in untreated than in treated silage. The reverse was true for acetic acid concentrations. When exposed to air, growth of yeasts and molds was delayed in ammonia-treated silage. In a second experiment, various levels (0.1 to 0.3%, fresh weight) of ammonium-N or a preservative with buffered propionic acid were added to whole-plant corn and allowed to ensile for 106 d. Silage treated with ammonia had a greater ratio of L- to D-lactic acid than did other silages. Untreated silage was aerobically stable for 32.3 h, whereas the low (42 h) and moderate (52.7 h) concentrations of both additives numerically improved aerobic stability. High concentrations of ammonia-N (0.3%) or a buffered propionic acid preservative (0.3%), markedly improved the aerobic stability of corn silage (82 and 69 h for ammonia and propionic acid-treated silage, respectively).

Bioadhesive-based dosage forms: the next generation

Prolonged contact time of a drug with a body tissue, through the use of a bioadhesive polymer, can significantly improve the performance of many drugs. These improvements range from better treatment of local pathologies to improved drug bioavailability and controlled release to enhanced patient compliance. There are abundant examples in the literature over the past 15 years of these improvements using first generation or "off-the-shelf" bioadhesive polymers. The present mini-review will remind us of the success achieved with these first-generation polymers and focus on proposals for the next-generation polymers and attendant benefits likely to occur with these improved polymeric systems.

Carrier-enhanced human growth hormone absorption across isolated rabbit intestinal tissue

Small molecular weight alpha acid derivatives are able to enhance the intestinal absorption of human growth hormone through isolated rabbit intestinal tissue. The enhancement is not through the usual tissue modification associated with traditional penetration enhancers nor is it through an active transport process. Rather these small molecules associate with human growth hormone in solution to make it more transportable through intestinal tissue. It is shown that the enhancer has specificity for a particular protein and the enhancer and human growth hormone must be in solution together to be effective, i.e. pretreating the tissue with enhancer and then adding the protein does not increase tissue permeability. Moreover, the enhancer does not increase the permeability of mannitol or progesterone, thus providing additional evidence of specificity and establishing that these agents are not classical penetration enhancers.

Transport of human growth hormone across Caco-2 cells with novel delivery agents: evidence for P-glycoprotein involvement

Emisphere Technologies, Inc. has synthesized a series of small molecules which have been shown to improve protein absorption through mucosal tissue. This enhancement is specific between protein and a particular delivery agent. Despite the specificity of interaction, the mechanism of enhanced tissue penetration is still unclear. The purpose of this work is to understand the enhancement mechanism(s) of these delivery agents by using Caco-2 cells as a model membrane. It was found that the bidirectional transepithelial fluxes of human growth hormone (hGH) in the presence of these delivery agents across human intestinal epithelial Caco-2 cell line showed marked asymmetry. Average permeability coefficient values obtained in the apical (AP) to basolateral (BL) direction were lower than those of the reverse (BL to AP) direction. On the other hand, the fluxes for human growth hormone alone were symmetric. When P-glycoprotein inhibitors were included in the transport medium, the permeability coefficient values of BL to AP direction were significantly decreased while the transport was increased in the reverse direction in the presence of delivery agents. P-glycoprotein inhibitors had no effect on the transport of human growth hormone alone. This study shows that human growth hormone alone can be transported across Caco-2 cells in very limited quantities by passive diffusion, but in the presence of delivery agents, human growth hormone can be effluxed in a P-glycoprotein-mediated fashion. This also indirectly shows that the human growth hormone has become more lipophilic in the presence of delivery agents.

Transcellular and lipophilic complex-enhanced intestinal absorption of human growth hormone

PURPOSE

To evaluate the transcellular mechanism of novel enhancers absorption enhancement of human growth hormone (hGH), by examining the involvement of a P-glycoprotein-like efflux system, changes in membrane fluidity, and membrane damage.

METHODS

Caco-2 cell monolayers were grown on Snapwell filter supports and placed in a side-by-side diffusion apparatus. Transport in both the apical to basolateral (AP to BL) and basolateral to apical (BL to AP) direction was measured at different temperatures and in the presence of potential inhibitors. Fluorescence anisotropy measurement was used to measure membrane fluidity. The fluorescence anisotropy of DPH- and TMA-DPH-labeled cell suspensions was measured at room temperature. LDH (a measure of cytosolic lactate dehydrogenase) leakage assay was used to evaluate cytotoxicity.

RESULTS

The bi-directional transepithelial fluxes of hGH in the presence of these novel enhancers across Caco-2 cells showed marked asymmetry. Average permeability coefficient values obtained in the apical to basolateral (AP to BL) direction were lower than those of the reverse (BL to AP) direction. On the other hand, the fluxes for hGH alone were symmetric. When P-gp-like efflux inhibitors were included in the transport medium, the permeability coefficient value of BL to AP direction was significantly decreased while the transport was increased in the reverse direction in the presence of novel enhancers. In addition, lowering the temperature to 25 degrees C completely eliminated the asymmetry of hGH transport in the presence of novel enhancers. It was also shown by fluorescence anisotropy that these novel enhancers alone only slightly increased membrane fluidity. On the other hand, upon addition of hGH to the novel enhancers, the cell membrane showed a dramatic change as compared to treatment with novel enhancers alone. The results from the LDH assay showed that the novel enhancers and/or hGH did not cause cell damage, at least up to 1 hour, and the damage seen at the 2 hour point is also much lower than other known enhancers.

CONCLUSIONS

This study shows that human growth hormone alone cannot be transported across Caco-2 cells, except in small quantities, by passive diffusion, but in the presence of novel enhancers, human growth hormone permeation is substantial. In addition, the asymmetry of transport of the complexed hGH appears to be due to a P-gp-like efflux system. Assuming that the present substrate specificity of the P-gp-like efflux system shows the same preference for hydrophobic molecules as p-gp, the present work also indirectly shows that human growth hormone has become more lipophilic in the presence of these novel enhancers. Furthermore, membrane fluidity data also supports the premise that these novel enhancers interact and stabilize hGH, to make them more hydrophobic and easier to be transported through cell membranes.

The natural history of mental disorder in old age: Alzheimer's disease and depressive illness compared

BACKGROUND

Depressive illness (DI) and Alzheimer's disease (AD) are important causes of morbidity in old age and the relationships between these two disorders are uncertain.

METHOD

In a prospective, descriptive, comparative study of consecutive referrals aged over 65 years to one consultant, 218 patients with AD and 280 patients with DI were followed up for 15 years.

RESULTS

The prognosis of DI uncomplicated by physical illness at referral was reasonably good and 5-year survival was double that of AD. The rate of occurrence of AD in DI is no greater than in the general population. The higher mortality from cancer in DI than in AD is unexplained but may relate to differences in aetiology of these two disorders.

CONCLUSION

Although their symptoms frequently overlap, AD and DI are distinct disorders with very different prognoses and accurate diagnosis may have important implications for appropriate treatment.

Scleral permeability to hydrocortisone and mannitol in the albino rabbit eye

To further explore barrier properties of the sclera, the diffusion of 3H-hydrocortisone and 14C-mannitol was measured across isolated rabbit scleral membrane. In vitro permeability studies were performed using side by side diffusion cells. Bicarbonated Ringer Solution with oxidized glutathione (GBR) at pH 7.4 was the perfusion medium, and the temperature was kept at 37 degrees C. Diffusion of hydrocortisone through the cornea was also measured to compare scleral and corneal permeation. Scleral permeability was found to be five times greater than corneal permeability. Drug analyses were performed by radionuclide counting (LSC), and permeability coefficients were obtained. In vitro metabolism of hydrocortisone was examined by incubation of tissue in hydrocortisone solution in GBR for 5 hours and 37 degrees C. Permeability coefficients of hydrocortisone diffusion through the sclera were also obtained at 25 degrees C, 15 degrees C, and 5 degrees C. Activation energy of scleral transport of hydrocortisone was calculated from an Arrhenius plot. The low activation energy suggests an aqueous pore pathway unlike permeation of the drug across the cornea which uses a transcellular pathway.

Mechanistic studies on effervescent-induced permeability enhancement

PURPOSE

To determine the mechanism(s) by which effervescence induces penetration enhancement of a broad range of compounds ranging in size, structure, and other physiocochemical properties across rat and rabbit small intestinal epithelium.

METHODS

Effervescent induced penetration enhancement was investigated in vitro by utilization of a modified Ussing chamber diffusion cell apparatus and in vivo by single-pass intestinal perfusion.

RESULTS

Carbon dioxide (CO2) bubbling directly onto rabbit ileum epithelium induced an increase in drug permeability. Mechanistic studies indicated that effects due to CO2 bubble evolution, such as increased drug dissolution rates, mucus thinning/stripping, and pH buffer effects did not contribute to increases in drug flux. Cellular enzyme (5'-ND and LDH) and total protein release assays did not indicate cell membrane perturbation and/or damage. CO2 bubbling induced a reduction in transepithelial electrical resistance (TEER) indicating epithelial disruption due to a structural change of the paracellular pathway. This was further substantiated by a MW dependence on paracellular marker flux. In addition, tissue recovery was relatively rapid, approximately 20 min.

CONCLUSIONS

CO2 bubbling directly onto the intestinal epithelium induced enhanced drug permeability due to an alteration of the paracellular pathway. This, in addition to fluid flow and membrane hydrophobicity concepts, may account for observed increases in drug flux.

Partially unfolded proteins efficiently penetrate cell membranes--implications for oral drug delivery

We have previously reported on the biological activity of members of a library of low molecular weight compounds (carriers) that enable the oral delivery of proteins (Milstein, Proceedings of the 1995 Miami Bio/Technology Winter Symposium on Protein Engineering and Structural Biology, IRL Press at Oxford University Press, 1995, p. 13; Leone-Bay et al., J. Med. Chem. 38 (1995) 4263-4269; Leone-Bay et al., J. Med. Chem. 39 (1996) 2571-2578; [1-3]). When rats or primates are orally administered a solution of carrier and either recombinant human alpha-interferon (rhIFN), insulin or recombinant human growth hormone (rhGH) significant serum concentrations of the proteins are detectable. The transport activity of these compounds is positively correlated with their structural effects on the protein molecules. Direct measurement of the interaction of these carrier molecules with the proteins indicates that they reversibly destabilize the native state of the molecule favoring a partially unfolded conformation. Apparently these intermediate protein conformations are transport competent and are able to be absorbed through the intestinal tissue and into the bloodstream. Since the measured binding of the carriers to the partially unfolded proteins is relatively weak (Kb = 100 M(-1)) and the systemic activity of the proteins appears to be unaffected, the changes in the structure of the proteins are manifestly reversible.

Differential induction of apoptosis by fludarabine monophosphate in leukemic B and normal T cells in chronic lymphocytic leukemia

Fludarabine (F-ara-A), an adenine nucleoside analog with efficacy in B-cell chronic lymphocytic leukemia (B-CLL), has also been shown to have a long-lasting suppressive effect on T lymphocytes. In heterogeneous clinical samples, apoptosis cannot be detected by standard methods in small cellular subsets. We developed, therefore, a combined assay of in situ end-labeling of nicked DNA by terminal deoxynucleotide transferase, with measurements of cellular DNA content and surface antigens (CD3, CD4, CD8, and CD19) by multiparametric flow cytometry. This assay was used to determine F-ara-A-induced apoptosis in different lymphocyte subsets from CLL patients and normal controls treated with F-ara-A in vitro. Apoptosis was also correlated to bcl-2 protein levels. We observed a direct effect of F-ara-A on both B-CLL and T lymphocytes. The response to F-ara-A in B-CLL lymphocytes in vitro was Rai stage-dependent, the early-stages being more responsive (P = .01). Higher levels of spontaneous apoptosis were observed in B-CLL lymphocytes from early stage patients (P = .02). No difference was observed in spontaneous apoptosis of normal T cells in B-CLL, although T lymphocytes in late-stage disease were more sensitive to F-ara-A-induced apoptosis. Incubation with cyclosporin A did not affect B-CLL and T-lymphocyte survival compared with control cultures. Results suggested a direct apoptotic effect of F-ara-A on B-CLL lymphocytes that decreases with increasing clinical stage. No correlation was found between bcl-2 and spontaneous or F-ara-A-induced apoptosis. Apoptosis occurred at all cell-cycle stages and was not restricted to cells in S phase. The mechanisms of this stage-dependent apoptosis in CLL remain to be elucidated.

Reliability of the Manitoba Mental Health Management Information System for Research

OBJECTIVES

To determine the accuracy of data contained in Manitoba's Mental Health Management Information System (MHMIS) as compared with client charts and to determine which factors influence completeness and accuracy.

METHODS

Data on diagnosis, open date and close date, demographic information, and contact information were obtained from client charts and compared with data extracted from the MHMIS. Semistructured interviews were conducted with individuals who contribute data to the MHMIS.

RESULTS

Data on required demographic variables, primary diagnosis, and open and close dates are highly similar in the 2 sources. The correlation between data sources on the number of client contacts is also good.

CONCLUSION

This study establishes the reliability of MHMIS data. MHMIS data, in combination with hospital abstracts and physician claims data, provide the information needed to serve as a psychiatric case register (PCR) and can be used for psychiatric epidemiology as well as for planning, monitoring, and evaluating mental health services.

Estimating the burden of disease. Comparing administrative data and self-reports

OBJECTIVES

A cardiovascular health survey of a representative sample of the adult population of Manitoba, Canada was combined with the provincial health insurance claims database to determine the accuracy of survey questions in detecting cases of diabetes, hypertension, ischemic heart disease, stroke, and hypercholesterolemia.

METHODS

Of 2,792 subjects in the survey, 97.7% were linked successfully using a scrambled personal health insurance number. Hospital and physician claims were extracted for these individuals for the 3-year period before the survey.

RESULTS

The authors found no benefits to using restrictive criteria for entrance into the study (ie, requiring more than one diagnosis to define a case). Using additional years of data increased agreement between data sources. Kappa values indicated high levels of agreement between administrative data and self-reports for diabetes (0.72) and hypertension (0.59); kappa values were approximately 0.4 for the other conditions. Using administrative data as the "gold standard," specificity was generally very high, although cases with hypertension and hypercholesterolemia (diagnosed primarily by laboratory or physical measurement) were associated with a lower specificity than the other conditions. Sensitivity varied markedly and was lowest for "other heart disease" and "stroke". For diabetes and hypertension, inclusion criteria calling for more than one diagnosis reduced the accuracy of case identification, whereas increasing the number of years of data increased accuracy of identification. For diabetes and hypertension, self-reports were fairly accurate in detecting "true" past history of the illness based on physician diagnosis recorded on insurance claims.

CONCLUSIONS

This study demonstrates the feasibility of linking a large health survey with administrative data and the validity of self-reports in estimating the prevalence of chronic diseases, especially diabetes and hypertension. A linked data set offers unusual opportunities for epidemiologic and health services research in a defined population.

Improved ocular bioavailability of indomethacin by novel ocular drug carriers

The ability of different drug carriers to improve the ocular bioavailability of drugs was investigated in the rabbit eye. The assayed drug carriers were suspensions of nanoparticles, nanocapsules and microparticles made of poly-epsilon-caprolactone (PECL) and a submicron emulsion. Results indicated that the three submicron systems, nanoparticles, nanocapsules and emulsion, increased more than 3-fold the indomethacin concentration in the cornea, aqueous humour and iris-ciliary body at 0.5 and 1 h post-instillation. Furthermore, an increased indomethacin ocular bioavailability of 300% was observed after instillation of the submicron systems in comparison with the value obtained for a commercial solution. In contrast, the microparticles hardly increased the ocular bioavailability of indomethacin. The mechanism of interaction of the colloidal carriers with the corneal epithelium was investigated by confocal laser scanning microscopy. Confocal images indicated that submicron particles penetrate into the corneal epithelium cells by an endocytic mechanism. The similar behaviour of the three colloidal carriers suggests that any of their specific ingredients (PCEL, lecithin and oil) acts as a penetration enhancer or an endocytotic stimulator. On the other hand, the favourable ocular penetration of indomethacin when encapsulated in the colloidal carriers, but not in the microparticles, led us to assume that the colloidal nature of these carriers is the main factor responsible for the increased ocular bioavailability of indomethacin. PECL nanoparticles and nanocapsules as well as submicron emulsions are shown to be novel corneal drug carriers, thus representing a useful approach for increasing the ocular bioavailability of drugs.

Primary amoebic meningoencephalitis after swimming in the Rio Grande

We report a case of fatal primary amoebic meningoencephalitis (PAM) with Naegleria fowleri in a 13-year-old male, and review the clinical course and diagnostic autopsy findings. The boy developed the infection after swimming with relatives in the Rio Grande and in a holding tank containing water pumped from the river. The clinical and neuropathologic features of PAM are presented. The microscopic features of motile unicellular organisms with pathognomonic broad, lobate pseudopodia are diagnostic and, if recognized before death, allow for timely treatment. A public health investigation into this case implicated river water from the Rio Grande polluted with sewage as the infection source. Exposure to polluted river water from some areas of the Rio Grande may represent a risk factor for infection with Naegleria fowerli, because the high levels of coliform bacteria found in sewage and the warm, sluggish water of the river are favorable growth conditions for the amoebae. Because the Rio Grande is an international border, this case illustrates the importance of international cooperation in pollution control in the prevention of a potentially fatal infectious disease.

Quality of attachment as a predictor of maternal visitation to young hospitalized children

Tested a comprehensive model of factors predicting maternal visitation with hospitalized children. Subjects were 86 mothers who completed the Spielberger State-Trait Anxiety Inventory, a 12-item attachment measure derived from the Waters and Deane Attachment Q-sort, and a demographic questionnaire. Children were 10 months to 4 years old (37 female, 49 male) and hospitalized for acute nonsurgical illness. Hierarchical regression analyses indicated that, of the subset of variables tested (SES, number of children at home, gender, age, number of previous hospitalizations, state anxiety, and security of attachment), quality of attachment was the only significant predictor of maternal visitation rate. Mothers who reported that their children displayed insecure attachment behaviors maintained a significantly lower rate of visitation than mothers who reported that their children displayed secure attachment behaviors. Results of this study highlight the importance of understanding parent-child attachment in predicting maternal visitation when a child is hospitalized.

Vaginal permeability and enzymatic activity studies in normal and ovariectomized rabbits

PURPOSE

This study was initiated to develop an animal model, using ovariectomized rabbits, for the post-menopausal human, based on in vitro vaginal tissue permeability and aminopeptidase activity.

METHODS

An enkephalin derivative [D-ala(2),N-methyl-phe(4)-glycol(5)][tyrosyl-3,5-(3)H] enkephalin {[(3)H] RX 783006), which has relative enzymatic stability to aminopeptidases and dipeptidyl peptidase, was used as a model peptide drug for permeability experiments. Aminopeptidase activity in vaginal homogenates, as well as in tissue pieces, was determined using 4-methoxy-2-naphthylamides of leucine, alanine, arginine, and glutamic acid as specific substrates. In addition, histological examination of normal and ovariectomized vaginal tissues was performed.

RESULTS

Vaginal permeability of the drug was significantly increased in the ovariectomized compared to the intact animal. The full vaginal tissue became thinner and mucosal epithelial thickness was reduced about two-fold after ovariectomization and vaginal cells from the castrated rabbit were typically immature. Aminopeptidase activity, leucine aminopeptidase, aminopeptidase B and A, was the same in vaginal tissue homogenates and whole-tissue specimens in both normal and ovariectomized rabbits whereas the activity of aminopeptidase N was significantly decreased in ovariectomized as compared to normal rabbits.

CONCLUSIONS

Based on the present data, the ovariectomized rabbit may be useful as an animal model for postmenopausal vaginal studies.

Skull base tumors. A critical appraisal and clinical series employing image guidance

Two of the most significant developments in neurosurgery over the past ten years have been the application of intraoperative navigational units and the widespread use of "skull base" surgical techniques. These developments have independently revolutionized the way in which neurosurgeons approach intracranial pathology. The combination of these two developments has had a profound effect in our clinical practice to improve outcome and extend our capabilities. This ability to see around the corner, "x-ray" vision as some have called it, provides an added measure of safety for the patient while allowing the surgeon to treat the lesion in a more aggressive fashion.

Hypermetaphase fluorescence in situ hybridization for quantitative monitoring of Philadelphia chromosome-positive cells in patients with chronic myelogenous leukemia during treatment

Using Philadelphia chromosome-positive (Ph+) chronic myelogenous leukemia (CML) as a model, our aim has been to develop a molecular cytogenetic method of high resolution analysis for monitoring the frequency of cells with nonrandom chromosome rearrangements in the bone marrow of patients receiving treatment for hematologic malignancies. Long-term exposure (24 hours) of bone marrow cultures to colcemid (0.1 microgram/mL) maximized a high frequency of metaphase collection. Such preparations were subjected to fluorescence in situ hybridization (FISH) using a 5 Mb probe that overlapped the region of the translocation at chromosome 9q34. This detected the Ph translocation in the resultant large number of overly contracted chromosome spreads. The procedure was validated and verified by studying 70 double-blind marrow samples from patients in different stages of Ph+ CML and from patients with Ph- hematologic malignancies (controls). This hypermetaphase FISH (HMF) method clearly identified Ph+ metaphases and allowed the analysis of 500 hypermetaphases per sample in less than 1 hour after FISH. HMF (1) identified statistically significant differences between the frequencies of Ph+ cells in samples that differed by less than 4%; (2) resolved such differences among patient samples that were all judged 100% Ph+ by standard G-band cytogenetics (CG); (3) resulted in the reclassification of response status in 23% of the patients initially classified by CG; (4) recognized Ph+ cells in 16% of patients characterized as having a complete cytogenetic response and in one patient with an original diagnosis of Ph- CML; and in one patient with an original diagnosis of Ph- CML; and (5) was informative where insufficient metaphases were obtainable for analysis by CG. HMF appears to be uniquely suitable for monitoring the status of patients with CML receiving treatment. It should also be applicable for patients with any hematologic diseases where chromosomal alterations are known and appropriate FISH probes are available.

Expression of basement membrane and endothelial cell adhesion molecules in vascular malformations of the brain: preliminary observations and working hypothesis

Little is known about the pathogenesis and subsequent cellular biologic behaviour of human cerebral vascular malformations. Innovative therapeutic strategies will depend on more fundamental understanding of structural and functional lesion biology. We have freeze-processed four specimens of arteriovenous malformation (AVM), two cavernous malformations (CM), and resected cortex from one case of Sturge-Weber disease (SWD) for immunohistochemical studies. Probes of vascular maturity and cellular adhesion were examined, including Factor 8 related antigen (F8RAG), laminin, fibronectin, and adhesion molecules VCAM, ELAM and ICAM-1 (CD 54). Sections of the same lesions were permanently fixed and stained using Haematoxylin and Eosin, and MOVAT Pentachrome stain for identification of vascular wall structures. A double antibody staining battery was utilized with ultraviolet fluorescent microscopy, and was analysed by an observer blinded to the antibody and lesion type. All malformations showed strong expression on their luminal endothelial surface for F8RAG. There was no expression of ELAM in any lesion. Two AVMs expressed VCAM on the endothelial surface of some vessels. ICAM-1 was expressed faintly within two AVMs. The CMs expressed fibronectin within the endothelium and subendothelial matrix, and both lesions were devoid of laminin expression. The AVMs and the SWD vessels stained for laminin, while none of the AVMs expressed fibronectin. These preliminary observations are consistent with the hypothesis that AVMs and SWD represent more mature vessels, consistent with possible lesion genesis during early phases of embryonic vascular development (dysvasculogenesis). In contrast, CMs represent immature vessels devoid of laminin and other features of mature vessels, consistent with ongoing dysangiogenesis within a fibronectin rich matrix. Further studies should be aimed at better elucidation of these biologic probes, and correlation with specific lesion behaviour.